Method and material for a thermally crosslinkable random copolymer

ABSTRACT

A structure that comprises a substrate; a cross-linked random free radical copolymer on the substrate; and a self-assembled patterned diblock copolymer film on the random copolymer; wherein the random copolymer is energy neutral with respect to each block of the diblock copolymer film. A method of making the structure is provided.

TECHNICAL FIELD

The present disclosure relates to the fabrication of convolvedself-assembled structures with deterministic patterning methodologies,and more specifically to nanostructures obtained using polymericself-assembly generated over a simple cross-linked polymeric underlayer.

BACKGROUND

The use of bottom-up approaches to semiconductor fabrication has grownin interest within the scientific community (for example seeThurn-Albrecht et al, Ultrahigh Nanowire Arrays Grown in Self-Assembled.Diblock Copolymer Templates, Science 290, 2126-2129, 2000 and Black etal. Integration of Self-Assembled Diblock Copolymers for SemiconductorCapacitor Fabrication, Applied Physics Letters, 79, 409-411, 2001). Onesuch approach utilizes block copolymers for generating sub-opticalground rule patterns. In particular, one illustrative use involvesforming a ‘honeycomb’ structure with a poly (methylmethacrylate-b-styrene) block copolymer. In the case of a cylindricalphase diblock having a minor component of PMMA, the PMMA block can phaseseparate to form vertically oriented cylinders within the matrix of thepolystyrene block upon a thermal anneal (Thurn-Albrecht et al, supra andBlack et al. supra).

This process is shown in FIGS. 1 a-1 c. A substrate PA2-100 isoptionally coated with a random copolymer PA2-110. This copolymer isaffixed to the surface and excess material is removed. A blockcopolymer. PA2-120 is, coated on the top surface of the random-substratestack as shown in FIG. 1 a. A key attribute of this approach is that theneutral surface energy underlayer copolymer be covalently bound to thesubstrate such that it is not removed during the application of thesubsequent diblock layer. Further, this underlayer polymer is preparedso that it will form a polymeric brush, i.e., having a single reactiveend group introduced by a special initiator. Also typical is therequirement that this underlayer polymer have relatively monodispersemolecular weight distribution. A requirement of the substrate is that ithas the necessary reactivity for the end group of the polymeric brush tocovalently bond to it. The block copolymer PA2-120 is annealed with heatand/or in the presence of solvents, which allows for phase separation ofthe immiscible polymer blocks PA2-121 and PA2-122 as shown in FIG. 1 b.The annealed film is then developed by a suitable method such asimmersion in a solvent/developer which dissolves one polymer block andnot the other, and reveals a pattern PA2-123 that is commensurate withthe positioning of one of the blocks in the copolymer. For simplicity,in FIG. 1 c the block is shown as completely removed although this isnot required.

Since block copolymers have a natural length scale associated with theirmolecular weight and composition, the morphology of a phase-separatedblock copolymer can be tuned to generate cylinders of a specific widthand on a specific pitch. Literature shows the use of UV exposure tocause the polymethylmethacrylate (PMMA) component of a typical diblockcopolymer to decompose into smaller molecules (see Thurn-Albrecht et al,supra) and, further, developed using glacial acetic acid to remove thesmall molecules. Others simply develop acetic acid to reveal the HCP(Hexagonal closed packed or hexagonal array of cylinders) pattern (Blacket al. supra). A third possible development technique involves using anoxygen plasma, which preferentially etches, for example, PMMA at ahigher rate than polystyrene, the other component of a typical diblockcopolymer (see Akasawa et al., Nanopatterning with Microdomains of BlockCopolymers for Semiconductor Capacitor Fabrication, Jpn. J. Appl. Phys.Vol 41, 2002, pp 6112-6118).

Recent literature demonstrates the self-aligned formation of diblockcopolymers within lithographically defined regions on a substrate. Thisprocess is shown in FIGS. 2 a-2 e. In FIG. 2 a, topography 3140 in amaterial 3130 is generated lithographically on a stack of materials3120, 3110 on a substrate 3100. The materials tack 3120 and 3110 canrepresent a single material or a stack of materials individually. InFIG. 2 b, a Diblock copolymer film 3150 is coated over the topography.In FIG. 2 c, the film is annealed allowing for phase separation in twoindividual components 3151 and 3152. In principle, there may be two ormore domains. In FIG. 2 d, a single domain of the Diblock is developedrevealing the pattern 3160. In principle, the pattern can be within thetrough or on top of the trough 3140 (shown in FIG. 2 a). The Diblock canbe partially developed as well. The resulting pattern can then betransferred into the material stack to generation a pattern 3170 asshown in FIG. 2 e.

Thus, previous embodiments entail forming an underlayer of neutralsurface energy [see Huang PhD Thesis, U. Mass, 1999] polymeric brushesof narrow polydispersity and limited reactivity requiring a suitablyreactive underlayer. This requires a reactive end group on the polymerbrush to be introduced via a specially prepared, initiator that was alsotypically utilized to control the molecular weight and polydispersity ofthe copolymer. This provides only a single reactive end group per chainwith which to bind to a suitable reactive substrate, e.g., the silanolgroups on a SiO₂ substrate. This is a limitation of this process.Additionally the reactivity of this system is limited by the singlereactive site of the end group requiring relatively long processingtimes. If the polymer brushes are not covalently bound to the substratethey would be removed during application of the subsequent diblock layerand formation of the aligned self-assembled domains would not occur orbe hampered. To this is added synthetic complexity of preparing suitableinitiators and unconventional polymerization techniques.

SUMMARY OF DISCLOSURE

This disclosure relates to a structure comprising;

a substrate;

a layer of a cross-linked random free radical copolymer over thesubstrate;

and a self-assembled patterned diblock copolymer film on the randomcopolymer; wherein the random copolymer is energy neutral with respectto each block of the diblock copolymer film.

In addition, the present disclosure relates to a method for providing astructure which comprises:

providing over a substrate a layer of a random free radical copolymer;

forming a film of a diblock copolymer on the random free radicalcopolymer;

wherein the random copolymer is energy neutral with respect to eachblock of the diblock copolymer film;

and further processing to thereby create a combined self-assembledpattern.

In other words, the present disclosure utilizes a crosslinked copolymerproviding a neutral surface energy film over which a diblock polymercomposition and process is performed that allows for a self-assembledstructure to form. This underlayer can be produced using standard freeradical polymerization processes and typical initiators and requires nospecial reactivity of the underlying substrate. Even in these cases itis found that improvements in processing and domain formation areachieved by the addition of the crosslinking component to the copolymer.

Still other objects and advantages of the present disclosure will becomereadily apparent by those skilled in the art from the following detaileddescription, wherein it is shown and described only in the preferredembodiments, simply by way of illustration of the best mode. As will berealized, the disclosure is capable of other and different embodiments,and its several details are capable of modifications in various obviousrespects, without departing from the intent of this disclosure.Accordingly, the description is to be regarded as illustrative in natureand not as restrictive.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 a-1 c are schematic diagrams illustrating a prior art process.

FIGS. 2 a-2 e are schematic diagrams illustrating an alternative priorart process.

BEST AND VARIOUS MODES FOR CARRYING OUT DISCLOSURE

The present disclosure utilizes a crosslinked copolymer providing aneutral surface energy film over which a diblock polymer composition andprocess is performed that allows for a self-assembled structure to form.This underlayer can be produced using standard free radicalpolymerization processes and typical initiators and requires no specialreactivity of the underlying substrate.

In one embodiment of the present disclosure, an energetically neutralcopolymer is provided which comprises cross-linkable units to immobilizea film of the copolymer after being applied to a substrate. Thecopolymer is typically, but not necessarily, a random free radicalcopolymer that contains minority component(s)/monomer(s) which arecopolymerized into the random copolymer and that are capable of enablingcrosslinking mechanisms. Examples of such components include but are notlimited to single or multifunctional crosslinking monomers.Additionally, the solution with the random copolymer can be formulatedwith other components that enable or promote reaction. Examples of suchcomponents are thermal acid generators, photoacid generators, photobasegenerators, thermal base generators, bases, acids or combinationsthereof.

Using such formulated random copolymer solutions, a film of the randomcopolymer may be coated on a substrate not previously compatible withtraditional ‘silanol’-based polymer brush formations. The randomcopolymer once coated may be post baked to drive off excess solventand/or thermally crosslinked. Optionally, the crosslinking may occurafter exposure to an actinic light source with an optional bake.Subsequent to random crosslinking, a film of the diblock copolymer isthen coated over the random copolymer. The structure is then subjectedto a thermal anneal sequence that ramps above the glass transitiontemperature of the film of the diblock copolymer, which may be less thanthat of the diblock polymer in its un-plasticized state The diblockpolymer film is allowed to organize into its energetically favoredstate. The film of the diblock polymer is allowed to cool. The film ofthe diblock polymer is then developed to reveal a combinedself-assembled pattern.

Typical anneal temperatures are on the order of about 100° C. to about200° C. for polymers with a glass transition temperature of at leastabout 100° C.; but more typically for diblocks and brush-basedrandoms >160° C. for the poly(styrene-b-MMA) systems. The addition ofthe thermal acid generators and/or photoacid generators allow forshorter and/or lower temperature bakes closer to about 100° C. to about150° C. although they are compatible with higher temperature bakes aswell.

The actinic light employed refers to any wavelength to which the diblockformulation is sensitive and is typically less than about 450 nm andmore typically less than about 365 nm.

The thickness of film of the random copolymer is typically about 3nanometers to about 1000 nanometers and more typically about 5nanometers to about 200 nanometers. Traditional ‘silanol based polymerbrushes’ are on the order of about 5 nm to about 12 nm in thickness. Theaugemented thickness of the random copolymer film is a benefit over theprior art. The thickness of film of the diblock copolymer is typicallyabout 10 nm to about 200 nm and more typically about 25 nm to about 80nm. The target thickness of the diblock is linked directly to thepolymer molecular weight and occurs in repeating block increments.

The random copolymer employed according to this disclosure is energyneutral with respect to each block of the diblock copolymer. In otherwords, the random copolymer does not interact preferentially with any ofthe blocks of the diblock copolymer. According to certain aspects of thedisclosure, the monomers that ate present in the random copolymer arethe same monomers that form the diblock polymer. This ensures energyneutrality for at least some composition of the monomers. Other methodscan be utilized that balance the surface energy components as well.However, below are disclosed some of the most readily accessible meansof generating a neutral surface.

Typical random copolymers employed according to this disclosure include(meth)acrylic acid esters (such as methyl methacrylate and isobutylmethacrylate); styrenic monomers (such as styrene and α-methyl styrene);vinylics (such as ethylene, propylene, vinyl acetate and vinyl chloride)and silicon containing materials (such as silisesquioxanes,carbosilanes, silanes and silizanes). The random copolymers include across-linkable monomer containing alkoxysilanes; (for exampletrimethoxysilane (TMOS)), epoxides (such as gycidyl methacrylate (GMA));styrenics (such as PHOST (phenoxystyrene)), and alcohols (such as HEMAand HEPA). The formulations may include reactive diluents such asmultifunctional ureas and multifunctional acrylates such as 2-ethoxymethacrylate and n-heptyl acrylate, thermal acid generators, photoacidgenerators, and quenchers such as weak bases to prevent inadvertentcrosslinking. Typically, the photosensitive systems are sensitive to ˜20mJ/cm² in conjuction with the presence of photoacid generators (andbaked at an appropriate temperature.)

The amount of the reactive monomer in the random copolymer is typicallya positive amount of <10 mole % of the composition, more typically apositive amount of <5 mole % and even mote typically a positive amountof <3 mole %.

The diblock polymers provide for a so-called self-assembly and includetwo immiscible polymer blocks A and B covalently bonded at one end. Ifthe molecules are given sufficient mobility (e.g., by annealing, byapplying an external electric field, or by other means), the two polymerblocks microphase separate, forming ordered, arrays of variousmorphologies.

Diblock copolymer phase morphologies include spherical, cylindrical,gyroid, and lamellar phases. The phase is typically determined by therelative molecular weight ratio of the two polymer blocks composing thediblock copolymer molecule. Typical ratios are: >80/20 for a sphericalphase, between about 60/40 and about 80/20 for a cylindrical phase, andbetween about 40/60 and about 60/40 for the lamellar phase. Exactcompositional range for each structure is dependent on the system butthese are provided as a reference. The characteristic dimensions ofdomains in self-assembled diblock copolymer films are typically about 5to about 200 nanometers and more typically about 10 nanometers to about100 nanometers. The domain dimensions can be controlled by changing thetotal molecular weight of the copolymer molecule. Again, the morphologyis defined by the mole fraction composition. Typically, the diblockcopolymer total molecular weight is in the range of about 10,000-about200,000 g/mol for self-assembled thin films that assemble in reasonabletimes.

Examples of suitable diblock copolymers arepolymethylmethacrylate-polystyrene or any of the following or similar:polybutadiene-polybutylmethcrylate, polybutadiene-polydimethylsiloxane,polybutadiene-polymethylmethacrylate, polybutadiene-polyvinylpyridine,polyisoprene-polymethylmethacrylate, polyisoprene-polyvinylpyridine,polybutylacrylate-polymethylmethacrylate,polybutylacrylate-polyvinylpyridine,polyhexylacrylate-polyvinylpyridine,polyisobutylene-polybutylmethacrylate,polyisobutylene-polydimethoxysiloxane,polyisobutylene-polymethylmethacrylate,polyisobutylene-polyvinylpyridine, polyisoprene-polyethyleneoxide,polybutylmethacrylate-polybutylacrylate,polybutylmethacrylate-polyvinylpyridine,polyethylene-polymethylmethacrylate,polymethylmethacrylate-polybutylacrylate,polymethylmethacrylate-polybutylmethacrylate, polystyrene-polybutadiene,polystyrene-polybutylacrylate, polystyrene-polybutylmethacrylate,polystyrene-polybutylstyrene, polystyrene-polydimethoxysiloxane,polystyrene-polyisoprene, polystyrene-polymethylmethacrylate,polystyrene-polyvinylpyridine, polyethylene-polyvinylpyridine,polyvinylpyridine-polymethylmethacrylate,polyethyleneoxide-polyisoprene, polyethyleneoxide-polybutadiene,polyethyleneoxide-polystyrene, polyethyleneoxide-polymethylmethacrylate.The benefit of the above structures is determined on a case by casebasis. For example, the polyethyleneoxide-polymethylmethacrylate diblockpolymer exhibits definitive solubility differences that enable selectiveremoval.

A benefit of the above structures containing both the random and diblockcopolymers is their high sensitivity to UV light. Typically, thesesystems are sensitive to ˜20 mJ/cm2. This is approximately 1000× moresensitive then the α-methyl styrene or MMA diblock copolymers reportedin the literature.

Those functionalized ran dorm formulations that impart a higher dosesensitivity than the prior art allow for reduced processing. As shown inDu et al., Additive-Driven Phase-Selective Chemistry in Block CopolymerThin Films: The Convergence of Top-Down and Bottom-Up Approaches,Advanced Materials, 2004, 16, No. 12, pages 953-957, June 17, Wiley-VCHVerlag GmbH & Co. KGaA, Weinheim, an initial exposure is used forphotoimaging, but a subsequent high intensity dose is used forphotodecomposition of the α-methylstyrene. Typically, low doses ate lessthan about 100 mJ/cm² and high doses are typically greater than about100 mJ/cm² and more typically about 0.5 J/cm² to about 10 J/cm². Thisdisclosure allows for a photo-induced solubility switch that in turnprovides for improved processability.

Benefits of the above structures are determined on a case by case basis.For example, a polyethyleneoxide-polymethylmethacrylate diblock polymerexhibits definitive solubility differences that enable selectiveremoval. Additionally, diblock copolymers of polydimethylsiloxane,polycarbosilanes, polysilsesquioxanes, and polymethylsilsesquioxaneswith organic blocks provide larger changes in etch selectivity.

In another embodiment, the energy neutral copolymer film contains athermally activated catalyst such as a thermal acid generator (TAG) toassist in controlling cross-linking reactivity. Examples of TAGs arenitrobenzyl sulfonates and phthalimido sulfonates. These are typicallypresent in positive amounts of <10 mole % by weight and more typicallypositive amounts of <5 mole % by weight.

In a still further embodiment, the cross-linking can take place byutilizing a reactive co-monomer along with a cross-linking additiverather than by relying solely on the reactivity of the copolymer.Examples of suitable components are multifunctional melamines,glycourils, benzylic alcohols, azides, epoxides and furans. Examples ofthese are tetrakis(methoxymethyl)glycouril, triphenylolmethanetriglygidyl ether and trisglycidyl isocyanurate. These are typicallypresent in positive amounts of <10 mole % and more typically about 2 toabout 5 mole %.

The following non-limiting examples are presented to further illustratethe present disclosure.

Example 1 Random Copoly(styrene-methyl methacrylate) with ReactiveBenzylic Alcohol End Group Prepared by Nitroxide-Mediated Free Radical,Polymerization

Styrene (4.8 g), methyl methacrylate (3.0 g), 3-(trimethoxysilyl)propylmethacrylate (0.5 g) and2,2,5-trimethyl-3-(1′-p-hydroxybenzylethoxy)-4-phenyl-3-azahexane (270mg) are dissolved in 1-methoxy-2-propanol (18.2 g) in a 3N RB flask andbrought to reflux under gentle nitrogen purge and then refluxed undernitrogen blanket. The reaction is refluxed for 21.5 hours and thenprecipitated into methanol (500 mL), filtered, rinsed with additionalmethanol and sucked dry overnight. White polymer (5.4 g) is obtainedwith Mw/Mn=12,000/10,000=1.2 containing 65 mole % incorporated styrene.

Example 2 Random Copoly(styrene-methyl methacrylate-trimethoxysilypropylmethacrylate) by Standard Free Radical Polymerization

Styrene (4.8 g), methyl methacrylate (2.85 g), 3-(trimethoxysilyl)propylmethacrylate (0.5 g) and 2,2′-azobis(2-cyanopentane) (0.3 g) aredissolved in 2-butanone (40 mL) and degassed using five vacuum/nitrogenpurges. The reaction is refluxed for 24 hours and then precipitated intomethanol (1 L), filtered, rinsed with additional methanol and sucked dryovernight. White polymer is obtained with Mw/Mn=10,400/7,200=1.45.

Example 3 Random Copoly(styrene-methyl methacrylate-glycidylmethacrylate) by Standard Free Radical Polymerization

Styrene (4.8 g), methyl methacrylate (2.85 g), glycidyl methacrylate(0.3 g) and 2,2′-azobis(2-cyanopentane) (0.3 g) are dissolved in2-butanone (40 mL) and degassed using five vacuum/nitrogen purges. Thereaction is refluxed for 24 hours and then precipitated into methanol (1L), filtered, rinsed with additional methanol and sucked dry overnight.A white polymer is obtained with Mw/Mn=16,000/8,300=1.9

The term “comprising” (and its grammatical variations) as used herein isused in the inclusive sense of “having” or “including” and not in theexclusive sense of “consisting only of.” The terms “a” and “the” as usedherein are understood to encompass the plural as well as the singular.

All publications, patents and patent applications cited in thisspecification are herein incorporated by reference, and for any and allpurpose, as if each individual publication, patent or patent applicationwere specifically and individually indicated to be incorporated byreference. In the case of inconsistencies, the present disclosure willprevail.

The foregoing description illustrates and describes the presentdisclosure. Additionally, the disclosure shows and describes only thepreferred embodiments of the disclosure, but, as mentioned above, it isto be understood that it is capable of changes or modifications withinthe scope of the concept as expressed herein, commensurate with theabove teachings and/or skill or knowledge of the relevant art. Theembodiments described hereinabove are further intended to explain bestmodes known of practicing the disclosure and to enable others skilled inthe art to utilize the disclosure in such, or other, embodiments andwith the various modifications required by the particular applicationsor used disclosed herein. Accordingly, the description is not intendedto limit the invention to the form disclosed herein. Also, it isintended that the appended claims be constructed to include alternativeembodiments.

1. A method for providing a structure which comprises: providing over asubstrate a layer of about 5 nanometers to about 200 nanometers of arandom free radical copolymer of styrene, methyl methacrylate and areactive co-monomer selected from the group consisting of2,2,5-trimethyl-3-(1′-p-hydroxybenzylethoxy)-4-phenyl-3-azahexane,3-(trimethoxysilyl)propyl methacrylate and glycidyl methacrylate;wherein the amount of the reactive co-monomer is about 2 mole % to about5 mole %; heating to cause crosslinking of the random free radicalcopolymer; forming a film of about 25 nanometers to about 80 nanometersof a diblock copolymer of polymethylmethacrylate-polystyrene on therandom free radical copolymer; wherein the random copolymer is energyneutral with respect to each block of the diblock copolymer film; andfurther processing comprising annealing at temperatures of about 100° C.to about 200° C. to thereby create a combined self-assembled pattern. 2.The method of claim 1 wherein the reactive co-monomer is glycidylmethacrylate.
 3. The method of claim 1 wherein the reactive co-monomeris 3-(trimethoxysily)propyl methacrylate.
 4. The method of claim 1wherein the reactive co-monomer is2,2,5-trimethyl-3-(1'-p-hydroxybenzylethoxy)-4-phenyl-3-azahexane.
 5. Amethod for providing a structure which comprises: providing over asubstrate a layer of a random free radical copolymer; forming a film ofa diblock copolymer on the random free radical copolymer; wherein therandom copolymer is energy neutral with respect to each block of thediblock copolymer film; and further processing to thereby create acombined self-assembled pattern, wherein said random copolymer includesa reactive cross-linking component, and wherein said random free radicalcopolymer is a random free radical copolymer of styrene, methylmethacrylate and a reactive co-monomer selected from the groupconsisting of2,2,5-trimethyl-3-(1'-p-hydroxybenzylethoxy)-4-phenyl-3-azahexane,3-(trimethoxysily)propyl methacrylate and glycidyl methacrylate; whereinthe amount of the reactive co-monomer is a positive amount less than 10mole %.
 6. The method of claim 5 wherein the layer of the randomcopolymer is about 3 to about 1000 nanometers thick and the film of thediblock polymer is about 10 nanometers to about 200 nanometers thick. 7.The method of claim 5 wherein the layer of the random copolymer is about5 to about 200 nanometers thick and the film of the diblock polymer isabout 25 nanometers to about 80 nanometers thick.
 8. The method of claim5 wherein said diblock copolymer is selected from the group consistingof polymethylmethacrylate-polystyrene,polybutadiene-polybutylmethcrylate, polybutadiene-polydimethysiloxane,polybutadiene-polymethylmethacrylate, polybutadiene-polyvinylpyridine,polyisoprene-polymethylmethacrylate, polyisoprene-polyvinylpyridine,polybutylacrylate-polymethylmethacrylate,polybutylacrylate-polyvinylpyridine,polyhexylacrylate-polyvinylpyridine,polyisobutylene-polybutylmethacrylate,polyisobutylene-polydimethoxysiloxane,polyisobutylene-polymethylmethacrylate, polyisobutylene-polyvinylpyridine, polyisoprene-polyethyleneoxide,polybutylmethacrylate-polybutylacrylate,polybutylmethacrylate-polyvinylpyridine,polyethylene-polymethylmethacrylate,polymethylmethacrylate-polybutylacrylate,polymethylmethacrylate-polybutylmethacrylate, polystyrene-polybutadiene,polystyrene-polybutylacrylate, polystyrene-polybutylmethacrylate,polystyrene-polybutylstyrene, polystyrene-polydimethoxysiloxane,polystyrene-polyisoprene, polystyrene-polymethylmethacrylate,polystyrene-polyvinylpyridine, polyethylene-polyvinylpyridine,polyvinylpyridine-polymethylmethacrylate,polyethyleneoxide-polyisoprene, polyethyleneoxide-polybutadiene,polyethyleneoxide-polystyrene, polyethyleneoxide-polymethylmethacrylate.
 9. The method of claim 5 wherein said reactivecross-linking component includes least one member selected from thegroup consisting of alkoxysilanes, epoxides, styrenics, and alcohols.10. The method from claim 5 wherein said reactive cross-linkingcomponent is comprised of at least one member selected from the groupconsisting of melamines, glycourils, benzylic alcohols, azides,epoxides, and furans.
 11. The method of claim 5 wherein said layer ofrandom free radical copolymer further comprises a thermally activatedTAG to induce crosslinking during heating.
 12. The method of claim 5wherein said layer of random free radical copoymer further comprises aphotolytically activated PAG to induce crosslinking, and wherein themethod further comprises photolysis and subsequent heating of thestructure.
 13. The method of claim 5 wherein said layer of random freeradical copolymer contains basic quenchers to stabilize the formulationfrom effects of acidic components.
 14. The method of claim 5 whichcomprises subjecting the structure to a thermal anneal, exposingportions of the structure to actinic light and baking at a temperaturethat allows for a chemical reaction to occur selectively in either theexposed or unexposed portions.
 15. The method of claim 5 which furthercomprises annealing at temperatures of about 100° C. to about 200° C. tothereby create a combined self-assembled pattern.
 16. The method ofclaim 5 wherein the reactive co-monomer is glycidyl methacrylate. 17.The method of claim 5 wherein the reactive co-monomer is3-(trimethoxysilyl)propyl methacrylate.
 18. The method of claim 5wherein the reactive co-monomer is2,2,5-trimethyl-3-(1'-p-hydroxybenzylethoxy)-4-phenyl-3-azahexane.